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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 21 |
| 3 | 143 |
| 4 | 953 |
| 5 | 6347 |
| 6 | 42285 |
| 7 | 281719 |
| 8 | 1876913 |
| 9 | 12504659 |
| 10 | 83310469 |
| 11 | 555043871 |
| 12 | 3697898985 |
| 13 | 24636713627 |
| 14 | 164138517789 |
| 15 | 1093548978567 |
| 16 | 7285610864737 |
| 17 | 48539321706403 |
| 18 | 323386164243445 |
| 19 | 2154513238908591 |
| 20 | 14354130788161817 |
[3,21,143,953,6347,42285,281719,1876913,12504659, 83310469,555043871,3697898985,24636713627, 164138517789,1093548978567,7285610864737, 48539321706403,323386164243445,2154513238908591, 14354130788161817] |